The present invention relates to a polishing composition to be used for polishing synthetic resin products, metal products, and the like.
A polishing composition disclosed in Japanese Laid-Open Patent Publication No. 7-11239 contains water, aluminum oxide, and a polishing accelerator including at least two selected from aluminum nitrate, glycol, and an alumina sol. The polishing composition is used for polishing, for example, synthetic resin products such as a plastic lens or metal products such as a disk substrate.
Increase of the rate at which an object is polished by a polishing composition, that is, the polishing rate of a polishing composition for an object, is always demanded for a polishing composition. The polishing rate of a polishing composition can generally be increased by increasing the amount of an abrasive or a polishing accelerator contained in the polishing composition. However, an increase in the amount of an abrasive causes an increase in cost and an excessive increase in viscosity of the polishing composition. If the viscosity of the polishing composition is excessively high, the handling properties and antifoaming properties of the polishing composition are reduced. Moreover, a polishing composition with excessively high viscosity causes the adherence of solids in the polishing composition on the inner wall of a polishing machine or the surface during polishing, and makes it difficult to stabilize the supply of the polishing composition to the polishing machine. On the other hand, an increase in the amount of a polishing accelerator makes the operator's hands rough, and causes corrosion of the polishing machine.
In the polishing composition disclosed in the above publication, for example, an increase in the amount of aluminum oxide or glycol such as propylene glycol and ethylene glycol allows a certain increase in the polishing rate of the polishing composition. However, the increase in the polishing rate by the increase in the amount of glycol or aluminum oxide cannot fully compensate negative effects caused by the increase in the amount of glycol or aluminum oxide.